In the 2017 National Defense Authorization Act — a 1,500-plus-page document that authorizes appropriations for the Departments of Defense and Energy — only one section concerns the life of the A-10. Yet it is sufficient to reinvigorate an argument that began in Congress several years ago.

The section in question prohibits the Air Force from retiring any A-10 aircraft or making a substantial change to that jet’s weapons system manning levels until two separate events take place. The first is the completion of the initial operational test and evaluation (IOT&E) for the F-35. That process was already mandated and funded, but the IOT&E start date has likely slipped until 2018.

The second directive requires the Air Force to conduct a comparison, a fly-off, that pits the capabilities of the F-35A against the A-10C across the latter’s current three-fold mission set: close-air support (CAS), combat search and rescue (CSAR), and forward air control-airborne (FAC-A).

The NDAA leaves much about the fly-off unknown. How will it be framed? How will it be funded? And what will the results tell us that we don’t already know?

The A-10 weapons system has been the cornerstone of the Air Force’s commitment to support the Army since it was introduced in the 1970s. The jet was designed to provide close-air support in the high-threat environment associated with the 1980s and 1990s. Its impressive capacity for ordnance, 30 mm cannon, loiter time and high-visibility cockpit make it a natural for delivering aerial firepower in close proximity to ground troops.

The A-10’s redundant flight controls, titanium armor and engines give it unmatched survivability in a shoulder-fired surface-to-air missile environment. It would have thrived in the threat environment associated with a European scenario before the fall of the Iron Curtain. But, just like every other fourth or four-plus generation fighter, it would not likely survive a single mission flown against the anti-access/area denial threats of today. That is where the F-35 was designed to operate.

The Lightning II’s stealth design allows it to operate within the threat rings of the two most advanced surface-to-air missile threats in the world today, the Russian S-300 and S-400. Its air-to-surface ordnance capacity in a stealth mode is limited, but cockpit visibility is good, and the jet’s situational awareness aids are unmatched. When the threat allows services to compromise stealth and reconfigure the F-35, its ordnance capacity and station time are all but a match for the A-10, and well exceed those of the F-16, F/A-18 and AV-8B. With that, where do the differences lie, and what would be gained by a fly-off.

Twenty-three highly experienced CAS, CSAR and FAC-A pilots who flew the A-10, F/A-18 and AV-8B, and who are now flying the F-35 were interviewed to compare their fourth-generation jets with the faculties of the F-35. The results of those conversations were decidedly mixed.

All 23 pilots picked the F-35 over their previous fighter for CAS missions in a high-threat environment. However, more than half picked their fourth-generation jets over the F-35 for CAS in low-threat situations. Those preferring their previous jet over the Lightning II cited current software and hardware limitations that do not allow targeting and employment options available to them in their previous jets. For example they mentioned hands-on switching between electro-optical and infrared sensors.

They also cited limitations on the type of munitions the F-35 can carry. While those capabilities will be added through programmed upgrades, the survey was taken with the jets as they are currently configured.

The combat search-and-rescue and forward air control-airborne missions are two of the most demanding in any environment due to the number of players and the complexities involved. The primary job of a pilot leading those missions is to coordinate, control and direct the employment of ordnance carried by other aircraft. Here, a premium is placed on a pilot’s ability to build and maintain situational awareness.

Link-16 has helped further situational awareness within those missions, but for most fourth-generation aircraft, situational awareness is built through radio transmissions that allow pilots to form a mental picture of the situation, and by taking notes regarding aircraft type, location, altitude, and the likes on knee-boards or on canopies using grease pencils. Visually acquiring and keeping tabs on friendly aircraft presents a whole different challenge. Here, the Lightning II has the upper hand.

The sensor suite of the F-35 provides most critical mission information to the pilot through cockpit displays that form a “God’s eye” view of the air and ground situation surrounding the tactical event. All the while, many of those same sensors, including the jet’s six distributed aperture system ports, are constantly scanning for threats and tracking every friendly aircraft. The jet projects relevant information — including cues for every friendly and enemy aircraft — directly onto the pilot’s helmet visor.

Thus, the F-35 lets pilots immediately see every other airborne player with a simple turn of the head. This allows them to employ ordnance from supporting aircraft quicker and more effectively than any other weapons system.

Every experienced pilot interviewed preferred the F-35 to their previous fighter in the CSAR and FAC-A roles in every threat environment — hands down.

IOT&E will not begin until the F-35’s 3F software modification is fielded, delivering a greater selection of ordnance and employment options for pilots flying any of the three missions in question. Improvements allowing sensor options and other capabilities that further the close-air support mission won’t be available until the Block 4 hardware modification is completed. That means little will change regarding low-threat CAS capabilities or preferences by the time either IOT&E or a potential fly-off is completed.

Congress rightly put the brakes on retiring the A-10, but the only thing a fly-off will prove is what we already know. Low-threat and low-intensity conflicts will be with us for some time to come, and the A-10 will continue to play a critical role in that environment. While a fly-off would be futile, Congress needs to keep the heat on the Air Force to sustain the A-10 as a viable component within our arsenal for the foreseeable future.

John Venable is a senior research fellow in The Heritage Foundation’s Center for National Defense. He is a former command pilot with more than 4,400 hours of flying time, including more than 300 hours in combat.